Proximity-Effect-Induced Anisotropic Superconductivity in a Monolayer Ni-Pb Binary Alloy Yen-Hui Lin, Chia-Hsiu Hsu, Iksu Jang, Chia-Ju Chen, Pok-Man Chiu, et al. ACS Applied Materials and Interfaces, 2022 A proximity effect facilitates the penetration of Cooper pairs that permits superconductivity in a normal metal, offering a promising approach to turn heterogeneous materials into superconductors and develop exceptional quantum phenomena. Here, we have systematically investigated proximity-induced anisotropic superconductivity in a monolayer Ni-Pb binary alloy by combining scanning tunneling microscopy/spectroscopy (STM/STS) with theoretical calculations. By means of high-temperature growth, the (33×33)R30o Ni-Pb surface alloy has been fabricated on Pb(111) and the appearance of a domain boundary as well as a structural phase transition can be deduced from a half-unit-cell lattice displacement. Given the high spatial and energy resolution, tunneling conductance (dI/dU) spectra have resolved the reduced but anisotropic superconducting gap ΔNiPb ≈ 1.0 meV, in stark contrast to the isotropic ΔPb ≈ 1.3 meV. In addition, the higher density of states at the Fermi energy (D(EF)) of the Ni-Pb surface alloy results in an enhancement of coherence peak height. According to the same Tc ≈ 7.1 K with Pb(111) from the temperature-dependent ΔNiPb and the short decay length Ld ≈ 3.55 nm from the spatially monotonic decrease of ΔNiPb, both results are supportive of a proximity-induced superconductivity. Despite a lack of a bulk counterpart, the atomically thick Ni-Pb bimetallic compound opens a pathway to engineer superconducting properties down to the two-dimensional limit, giving rise to the emergence of anisotropic superconductivity via a proximity effect.
How dissociated fragments of multiatomic molecules saturate all active surface sites—H2O adsorption on the Si(100) surface Chan-Yuen Chang, Cheng-Yu Lin, Deng-Sung Lin Journal of Physics Condensed Matter, 2021 A fundamental question for the adsorption of any gas molecule on surfaces is its saturation coverage, whose value can provide a comprehensive examination for the adsorption mechanisms, dynamic and kinetic processes involved in the adsorption processes. This investigation utilizes scanning tunneling microscopy to visualize the H2O adsorption processes on the Si(100) surface with a sub-monolayers (<0.05 ML) of chemically-reactive dangling bonds remaining after exposure to (1) a hydrogen atomic beam, (2) H2O, and (3) Cl2 gases at room temperature. In all three cases, each of the remaining isolated single dangling bonds (sDB) adsorb and is passivated by either of the two dissociation fragments, the H or OH radical, to form a surface Si–H and Si–OH species. A new adsorption mechanism, termed ‘dissociative and asynchronous chemisorption’, is proposed for the observation presented herein. Upon approaching a sDB site, the H2O molecule breaks apart into two fragments. One is chemisorbed to the sDB. The other attaches to the same or the neighboring passivated dimer to form a transition state of surface diffusion, which then diffuses on the mostly passivated surface and is eventually chemisorbed to another reactive site. In other words, the chemisorption reactions of the two fragments after dissociation occur at different and uncorrelated time and places. This adsorption mechanism suggests that a diffusion transition state can be an adsorption product in the first step of the dissociative adsorption processes.
Quantum well electronic states in spatially decoupled 2D Pb nanoislands on Nb-doped SrTiO3(0 0 1) Guan-Yu Chen, Chia-Hsiu Hsu, Bo-You Liu, Li-Wei Chang, Deng-Sung Lin, et al. Applied Surface Science, 2021 Two-dimensional (2D) Pb nanoisland has established an ideal platform for studying the quantum size effects on growth mechanism, electronic structures as well as high-temperature superconductivity. Here, we investigate the growth and quantum well electronic states of the 2D Pb nanoislands on Nb-doped SrTiO3(001) by scanning tunneling microscopy and spectroscopy. In contrast to Pb/Si(111), Pb/Cu(111) and Pb/Ag(111), there is no wetting layer of Pb formed on the Nb-doped SrTiO3(001) surface, resulting in isolated Pb nanoislands with an apparent height of 4 atomic layers as the building blocks for the island growth. According to the thickness-dependent quantum well states resolved in both occupied and unoccupied energy regions, the constant group velocity vg = 1.804 × 106 m/s and the Fermi wavevector kF = 1.575 A-1, have been extracted from a linear fit of the Pb(111) band dispersion along the Γ - L direction. In addition, the energy-dependent scattering phase shift φ(E) obtained by means of the phase accumulation model shows a metallic-like scattering interface analogous to Pb/Ag(111). These spatially decoupled 2D Pb nanoislands thus realize an opportunity to explore the intrinsic quantum confinement phenomena in nanoscale superconductors on the doped titanium-oxide-type substrate.
Orbital-enhanced warping effect in p x,p y-derived Rashba spin splitting of monatomic bismuth surface alloy Guan-Yu Chen, Angus Huang, Yen-Hui Lin, Chia-Ju Chen, Deng-Sung Lin, et al. Npj Quantum Materials, 2020 Spin-split Rashba bands have been exploited to efficiently control the spin degree of freedom of moving electrons, which possesses a great potential in frontier applications of designing spintronic devices and processing spin-based information. Given an intrinsic breaking of inversion symmetry and sizeable spin–orbit interaction, two-dimensional (2D) surface alloys formed by heavy metal elements exhibit a pronounced Rashba-type spin splitting of the surface states. Here, we have revealed the essential role of atomic orbital symmetry in the hexagonally warped Rashba spin-split surface state of the $$\\sqrt 3 \\times \\sqrt 3 R30^0$$ 3 × 3 R 3 0 0 BiCu2 monatomic alloy by scanning tunneling spectroscopy (STS) and density functional theory (DFT). From dI/dU spectra and calculated band structures, three hole-like Rashba-split bands hybridized from distinct orbital symmetries have been identified in the unoccupied energy region. Because of the hexagonally deformed Fermi surface, quasi-particle interference (QPI) mappings have resolved scattering channels opened from interband transitions of px,py (mj = 1/2) band. In contrast to the s,pz-derived band, the hexagonal warping is predominately accompanied by substantial out-of-plane spin polarization Sz up to 24% in the dispersion of px,py (mj = 1/2) band with an in-plane orbital symmetry.
Extended α-phase Bi atomic layer on Si(1 1 1) fabricated by thermal desorption Shin-Ching Hsieh, Chia-Hsiu Hsu, Han-De Chen, Deng-Sung Lin, Feng-Chuan Chuang, et al. Applied Surface Science, 2020 Two-dimensional materials with sizable spin-orbit coupling are not only interesting to fundamental studies, but also useful candidates for technological applications. Here, we report on the fabrication of extended α-phase Bi atomic layer on Si(1 1 1) surface by means of thermal desorption. The atomic and electronic structures have been investigated by combining scanning tunneling microscopy (STM) experiments with density functional theory (DFT) calculations. While β-phase Bi trimer with 3 × 3 R30° surface reconstruction can be prepared by room-temperature deposition with subsequent post annealing at 700 K, the α-phase Bi monomer only appears at 800 K due to thermal desorption with the Bi desorption rate of 0.26 ML/min. From our DFT calculations, the α-phase Bi shows Rashba energies ER = 15 meV and 3 meV at high symmetry points of M ¯ and K ¯ , respectively. Since α-phase Bi monomer represents isotropic lattice symmetry with a dilute Bi density, it may serve as a potential template to tune Rashba effect by incorporating with multiple elements.
Controlling the Polarity of the Molecular Beam Epitaxy Grown In-Bi Atomic Film on the Si(111) Surface Cho-Ying Lin, Chia-Hsiu Hsu, Yu-Zhang Huang, Shih-Ching Hsieh, Han-De Chen, et al. Scientific Reports, 2019 Synchrotron radiation core-level photoemission spectroscopy, scanning tunneling microscopy (STM), and first-principles calculations have been utilized to explore the growth processes and the atomic structure of the resulting films during the two-step molecular beam epitaxy (MBE) of In and Bi on the Si(111) surface. Deposition of 1.0-ML Bi on the In/Si(111)-(4 × 1) surface at room temperature results in Bi-terminated BiIn-(4 × 3) structures, which are stable up to ~300 °C annealing. By contrast, deposition of In on the β-Bi/Si(111)-(√3 × √3) surface at room temperature results in three dimensional (3D) In islands. In both cases, annealing at 460 °C results in the same In-terminated In0.75Bi/Si(111)-(2 × 2) surface. Our DFT calculations confirm that the surface energy of In-terminated In0.75Bi/Si(111)-(2 × 2) system is lower than that of Bi-terminated Bi0.75In/Si(111)-(2 × 2). These findings provide means for the control of the polarity of the MBE In-Bi atomically thick films.
Atomic-Scale Chemical Conversion of Single-Layer Transition Metal Dichalcogenides Peng Chen, Yun-Ting Chen, Ro-Ya Liu, Han-De Chen, Dengsung Lin, et al. ACS Nano, 2019 Chemical conversion by atomic substitution offers a powerful route toward the creation of unusual structures and functionalities. Here, we demonstrate the progressive transformation of single-layer TiTe2 into TiSe2 by reaction with a Se flux in vacuum. Angle-resolved photoemission spectroscopy and scanning tunneling microscopy reveal intriguing reaction patterns involving TiSe2 island ingrowth starting from the TiTe2 island edges, while the band structure and core level signatures of TiSe2 grow in intensity at the expense of those corresponding to TiTe2. Lattice mismatch between TiTe2 and TiSe2 results in misfit holes and lattice distortions over a distance behind a seamless fingerlike reaction front. The regions of TiSe2 and TiTe2 are distinguished by a height difference and a charge density wave (CDW) at different transition temperatures. The method of in situ chemical conversion offers opportunities for atomic-scale engineering of layered transition metal dichalcogenides that host useful properties arising from CDW, Dirac, Weyl, superconducting, spin-valley, and magnetic structures.
Large quantum-spin-Hall gap in single-layer 1T′ WSe2 P. Chen, Woei Wu Pai, Y.-H. Chan, W.-L. Sun, C.-Z. Xu, et al. Nature Communications, 2018 Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum-spin-Hall (QSH) effect, but experimental realization of such systems with a large band gap suitable for room-temperature applications has proven difficult. Here, we report the successful growth on bilayer graphene of a quasi-freestanding WSe2 single layer with the 1T′ structure that does not exist in the bulk form of WSe2. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we observe a gap of 129 meV in the 1T′ layer and an in-gap edge state located near the layer boundary. The system′s 2D TI characters are confirmed by first-principles calculations. The observed gap diminishes with doping by Rb adsorption, ultimately leading to an insulator–semimetal transition. The discovery of this large-gap 2D TI with a tunable band gap opens up opportunities for developing advanced nanoscale systems and quantum devices.The current known two-dimensional topological insulators with small band gaps limit the potential for room temperature applications. Here, Chen et al. observe a sizable gap of 129 meV in a 1T'-WSe2 single layer grown on bilayer graphene with in-gap edge state near the layer boundary.
Proximity-effect-induced anisotropic superconductivity in a monolayer Ni-Pb binary alloy YH Lin, CH Hsu, I Jang, CJ Chen, PM Chiu, DS Lin, CT Wu, FC Chuang, ... ACS Applied Materials & Interfaces 14 (20), 23990-23997 , 2022 2022 Citations: 5
Superconducting proximity effect in (root 7 x root 7) R19. 1 degrees Ni nanoislands on Pb (111) YH Lin, S Teh, TY Yeh, CH Chen, DS Lin, HT Jeng, PJ Hsu PHYSICAL REVIEW MATERIALS 6 (4) , 2022 2022
Superconducting proximity effect in Ni nanoislands on Pb(111) YH Lin, S Teh, TY Yeh, CH Chen, DS Lin, HT Jeng, PJ Hsu Physical Review Materials 6 (4), 046002 , 2022 2022 Citations: 2
Imaging buried objects with the hard/soft x-ray photoemission electron microscope CC Liu, Y Huang, TH Chuang, DS Lin, DH Wei Journal of Applied Physics 130 (17) , 2021 2021 Citations: 1
How dissociated fragments of multiatomic molecules saturate all active surface sites—H 2 O adsorption on the Si(100) surface CY Chang, CY Lin, DS Lin Journal of Physics: Condensed Matter 33 (40), 404004 , 2021 2021 Citations: 10
Quantum well electronic states in spatially decoupled 2D Pb nanoislands on Nb-doped SrTiO3 (0 0 1) GY Chen, CH Hsu, BY Liu, LW Chang, DS Lin, FC Chuang, PJ Hsu Applied Surface Science 537, 147967 , 2021 2021 Citations: 2
Orbital-enhanced warping effect in p x , p y -derived Rashba spin splitting of monatomic bismuth surface alloy GY Chen, A Huang, YH Lin, CJ Chen, DS Lin, PY Chang, HT Jeng, ... npj Quantum Materials 5 (1), 89 , 2020 2020 Citations: 8
Orbital-enhanced Warping Effect in P\textsubscript {x}, P\textsubscript {y}-derived Rashba Spin Splitting of Monatomic Bismuth Surface Alloy Surface Alloy GY Chen, A Huang, YH Lin, CJ Chen, DS Lin, PY Chang, HT Jeng, ... arXiv preprint arXiv:2006.05024 , 2020 2020
Extended α-phase Bi atomic layer on Si (1 1 1) fabricated by thermal desorption SC Hsieh, CH Hsu, HD Chen, DS Lin, FC Chuang, PJ Hsu Applied Surface Science 504, 144103 , 2020 2020 Citations: 9
Atomic-Scale Chemical Conversion of Single-Layer Transition Metal Dichalcogenides P Chen, YT Chen, RY Liu, HD Chen, D Lin, AV Fedorov, TC Chiang ACS nano 13 (5), 5611-5615 , 2019 2019 Citations: 7
Controlling the polarity of the molecular beam epitaxy grown in-bi atomic film on the si (111) surface CY Lin, CH Hsu, YZ Huang, SC Hsieh, HD Chen, L Huang, ZQ Huang, ... Scientific Reports 9 (1), 756 , 2019 2019 Citations: 8
Very different adsorption path ways of triatomic molecule H 2 O on isolated and domains of dangling bonds on the Si(100) surface CY Chang, DS Lin APS March Meeting Abstracts 2019, R45. 010 , 2019 2019
Growth of a predicted two-dimensional topological insulator based on InBi-Si(111)- CH Hsu, ZQ Huang, CY Lin, GM Macam, YZ Huang, DS Lin, TC Chiang, ... Physical Review B 98 (12), 121404 , 2018 2018 Citations: 31
HAXPES Study of Multilayer Oxidation Films on Si (100) C Lin, DS Lin SPring-8/SACLA Research Report 6 (2), 190-193 , 2018 2018
Tunable electronic structure and surface states in rare-earth monobismuthides with partially filled shell P Li, Z Wu, F Wu, C Cao, C Guo, Y Wu, Y Liu, Z Sun, CM Cheng, DS Lin, ... Physical Review B 98 (8), 085103 , 2018 2018 Citations: 59
Depth Dependence of the Photoelectron Emission Profile for Cathode Lens Microscopy Y Huang, TH Chuang, CI Lu, CH Huang, DS Lin, CC Kuo, DH Wei Microscopy and Microanalysis 24 (S2), 154-155 , 2018 2018
Large quantum-spin-Hall gap in single-layer 1T′ WSe2 P Chen, WW Pai, YH Chan, WL Sun, CZ Xu, DS Lin, MY Chou, ... Nature communications 9 (1), 2003 , 2018 2018 Citations: 204
Atomic and Electronic Structure of the In-Bi Bilayer on the Si (111) Surface× CY Lin, YZ Huang, HD Chen, DS Lin APS March Meeting Abstracts 2018, V17. 012 , 2018 2018
Growth of Ge and Si on Monolayer Silicene on Metal Surfaces DS Lin Elsevier , 2018 2018
MOST CITED SCHOLAR PUBLICATIONS
Large quantum-spin-Hall gap in single-layer 1T′ WSe2 P Chen, WW Pai, YH Chan, WL Sun, CZ Xu, DS Lin, MY Chou, ... Nature communications 9 (1), 2003 , 2018 2018 Citations: 204
Scanning-tunneling-microscopy studies of disilane adsorption and pyrolytic growth on Si (100)-(2x1) DS Lin, ES Hirschorn, TC Chiang, R Tsu, D Lubben, JE Greene Physical Review B 45 (7), 3494 , 1992 1992 Citations: 105
Thermal reactions of phosphine with Si (100): a combined photoemission and scanning-tunneling-microscopy study DS Lin, TS Ku, TJ Sheu Surface science 424 (1), 7-18 , 1999 1999 Citations: 85
Dimer charge asymmetry determined by photoemission from epitaxial Ge on Si (100)-(2× 1) DS Lin, T Miller, TC Chiang Physical review letters 67 (16), 2187 , 1991 1991 Citations: 80
Charge transfer and asymmetry on Ge (111)-c (2× 8) studied by scanning tunneling microscopy ES Hirschorn, DS Lin, FM Leibsle, A Samsavar, TC Chiang Physical Review B 44 (3), 1403 , 1991 1991 Citations: 77
Tunable electronic structure and surface states in rare-earth monobismuthides with partially filled shell P Li, Z Wu, F Wu, C Cao, C Guo, Y Wu, Y Liu, Z Sun, CM Cheng, DS Lin, ... Physical Review B 98 (8), 085103 , 2018 2018 Citations: 59
X-ray scattering study of Ag/Si (111) buried interface structures H Hong, RD Aburano, DS Lin, H Chen, TC Chiang, P Zschack, ED Specht Physical review letters 68 (4), 507 , 1992 1992 Citations: 58
Adsorption and thermal reactions of disilane and the growth of Si films on Ge (100)-(2× 1) DS Lin, T Miller, TC Chiang Physical Review B 47 (11), 6543 , 1993 1993 Citations: 53
Atomistics of Ge deposition on Si (100) by atomic layer epitaxy DS Lin, JL Wu, SY Pan, TC Chiang Physical review letters 90 (4), 046102 , 2003 2003 Citations: 49
Holography of Ge (111)− c (2× 8) by Surface Core-Level Photoemission MT Sieger, JM Roesler, DS Lin, T Miller, TC Chiang Physical review letters 73 (23), 3117 , 1994 1994 Citations: 47
Interaction of phosphine with Si (100) from core-level photoemission and real-time scanning tunneling microscopy DS Lin, TS Ku, RP Chen Physical Review B 61 (4), 2799 , 2000 2000 Citations: 45
Heterojunction confinement on the atomic structure evolution of near monolayer core–shell nanocatalysts in redox reactions of a direct methanol fuel cell TY Chen, GW Lee, YT Liu, YF Liao, CC Huang, DS Lin, TL Lin Journal of Materials Chemistry A 3 (4), 1518-1529 , 2015 2015 Citations: 44
Boundary-structure determination of Ag/Si (111) interfaces by x-ray diffraction RD Aburano, H Hong, JM Roesler, K Chung, DS Lin, P Zschack, H Chen, ... Physical Review B 52 (3), 1839 , 1995 1995 Citations: 39
Hydrogen-desorption kinetic measurement on the Si (100)-2× 1: H surface by directly counting desorption sites DS Lin, RP Chen Physical Review B 60 (12), R8461 , 1999 1999 Citations: 38
Adsorption and dissociation of Si2H6 on Ge (001) 2× 1 R Tsu, D Lubben, TR Bramblett, JE Greene, DS Lin, TC Chiang Surface science 280 (3), 265-276 , 1993 1993 Citations: 38
Growth process of Ge on Si (100)-(2× 1) in atomic-layer epitaxy from Ge 2 H 6 KH Huang, TS Ku, DS Lin Physical Review B 56 (8), 4878 , 1997 1997 Citations: 35
Surface segregation and growth‐mode transitions during the initial stages of Si growth on Ge(001)2×1 by cyclic gas‐source molecular beam epitaxy from Si 2 H 6 R Tsu, HZ Xiao, YW Kim, MA Hasan, HK Birnbaum, JE Greene, DS Lin, ... Journal of applied physics 75 (1), 240-247 , 1994 1994 Citations: 34
Influence of sapphire nitridation on properties of indium nitride prepared by metalorganic vapor phase epitaxy YC Pan, WH Lee, CK Shu, HC Lin, CI Chiang, H Chang, DS Lin, MC Lee, ... Japanese journal of applied physics 38 (2R), 645 , 1999 1999 Citations: 32
Si indiffusion on Ge (100)-(2× 1) studied by core-level photoemission DS Lin, T Miller, TC Chiang Physical Review B 45 (19), 11415 , 1992 1992 Citations: 32
Growth of a predicted two-dimensional topological insulator based on InBi-Si(111)- CH Hsu, ZQ Huang, CY Lin, GM Macam, YZ Huang, DS Lin, TC Chiang, ... Physical Review B 98 (12), 121404 , 2018 2018 Citations: 31
